In 1951, John Cage visited the anechoic chamber at Harvard University. An anechoic chamber is a room designed in such a way that the walls, ceiling, and floor absorb all sounds made in the room, rather than reflecting them as echoes. Such a chamber is also externally sound-proofed. Cage entered the chamber expecting to hear silence, but he wrote later, ‘I heard two sounds, one high and one low. When I described them to the engineer in charge, he informed me that the high one was my nervous system in operation, the low one my blood in circulation.’ Cage had gone to a place where he expected total silence, and yet heard sound. ‘Until I die there will be sounds. And they will continue following my death. One need not fear about the future of music.’

Cage’s realisation as he saw it of the impossibility of silence which led to the composition of 4′33″